Wind noise reduction for microphone

ABSTRACT

The present invention relates to wind noise reduction for a microphone ( 10 ) achieved by locating a microphone pick up ( 2 ) in a chamber ( 4 ) provided with at least one sound passage ( 5 ), wherein one or more elements (s) ( 6 ) is/are provided in the sound passage (s) ( 5 ) to decrease the speed of the air stream.

RELATED APPLICATIONS

The present application is a 35 U.S.C. 371 national phase application ofPCT International Application No. PCT/EP2004/005605, having aninternational filing date of May 25, 2004 and claiming priority toEuropean Patent Application No. 03076938.4, filed Jun. 6, 2003, toEuropean Patent Application No. 04000594.4, filed Jan. 14, 2004, and toU.S. Provisional Application No. 60/537,841 filed Jan. 21, 2004, thedisclosures of which are incorporated herein by reference in theirentireties. The above PCT International Application was published in theEnglish language and has International Publication No. WO 2004/112424A1.

BACKGROUND OF THE INVENTION

The present invention relates to a transmitter portion of a portableelectronic communication device and is concerned with reducingwind-noise produced by an undesired air stream blowing into amicrophone.

Conventionally, several types of so-called “non-directional microphones”have been used in transmitters provided in portable electroniccommunication devices such as cellular phones. However, although thesemicrophones are considered to be less sensitive to wind-noise from airblowing into the microphone compared to so-called “directionalmicrophones”, wind-noise is often still a problem. Therefore, noisecancelling algorithms are sometimes used to reduce this problem.However, a drawback is that due to power consumption, noise cancellingalgorithms are not always suitable in portable electronic devices havinglimited battery capacity.

Moreover, non-directional microphones also suffer from low signal toambient ratio, whereby noise or background sound can negativelyinfluence voice. Therefore, there is also a need to improve this, forinstance by using a directional microphone, which has a better signal toambient ratio compared to a non-directional microphone. However, since adirectional microphone is sensitive to wind noise, to be able to use theadvantage compared to a non-directional microphone, wind noisesensitivity needs to be reduced. Due to large power consumption noisecancelling algorithms are not suitable in portable devices as describedabove. Because of that, non-directional microphones have not foundwide-spread application among portable electronic devices of today.

Thus, there is a need of a microphone, in particular a directionalmicrophone, for a portable electronic device having low powerconsumption, good signal to ambient ratio, and being resistant to windnoise.

SUMMARY OF THE INVENTION

The present invention is thus directed towards providing a microphoneunit, in particular a directional microphone unit, for a portableelectronic device that has low power consumption, good signal to ambientratio, which device is resistant to wind noise.

Accordingly, an object of the invention is to provide a microphone for atelephone-transmitter to reduce wind-noise.

According to a first aspect of the invention, this is achieved bylocating a microphone in a chamber provided with at least one soundpassage, wherein one or more element(s) is/are provided in the soundpassage(s) to decrease the speed of the air stream.

A microphone unit according to the invention includes, in front of amicrophone pick up of the microphone unit a chamber. The chamber has apredetermined sectional area and volume, which together with the totalsectional area and volume of the sound passages, reduces the influenceof the undesired air stream.

A second aspect of the present invention is directed to a microphoneunit for a portable electronic device, comprising a microphone pick uplocated within a microphone pick up housing forming a chamber. Thechamber being provided with at least one sound passage opening forreceiving sound from outside the device, wherein said at least one soundpassage opening is provided with at least one wind noise reductionelement.

A third aspect of the present invention is directed to a microphone unitincluding the aspects of the second aspect, wherein said wind reductionelement comprises a mesh having one layer.

A fourth aspect of the present invention is directed to a microphoneunit including the aspects of the second aspect, wherein said wind noisereduction element comprises a mesh having a plurality of layers.

A fifth aspect of the present invention is directed to a microphone unitincluding the aspects of the third or the fourth aspect, wherein theratio between the chamber size and the density of the mesh is arrangedto maintain the directional pick up pattern of the microphone used.

A sixth aspect of the present invention is directed to a microphone unitincluding the aspects of the second to the fifth aspect, wherein themesh is made of metal.

A seventh aspect of the present invention is directed to a microphoneunit including the aspects of the second to the sixth aspect, whereinthe mesh is made of polymer material such as nylon.

An eighth aspect of the present invention is directed to a microphoneunit including the aspects of the second to the seventh aspect, whereinsaid housing extending in a longitudinal direction is a cylinder havinga jacket surface and a side surface.

A ninth aspect of the present invention is directed to a microphone unitincluding the aspects of the eight aspect, wherein said sound passageopening is a hole extending in the longitudinal direction in said mantlesurface.

A tenth aspect of the present invention is directed to a microphone unitincluding the aspects of the eight or ninth aspect, wherein said hole isa hole in said side surface.

An eleventh aspect of the present invention is directed to a microphoneunit including any one of the first to the tenth aspect, wherein saidmicrophone unit is a directional microphone.

A twelfth aspect of the present invention is directed to a microphoneunit according to any one of the first to the tenth aspects, whereinsaid microphone unit is non-directional.

These and other objects and advantages of the invention will be apparentfrom the following description taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view, of one embodiment of themicrophone unit of the invention;

FIG. 2 is a perspective view, of an embodiment of the microphone unit ofthe invention;

FIG. 3 is a schematic view of a mesh which was used to reducewind-noise; and

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention can be advantageously applied to all types ofmicrophones to reduce sensitivity to wind-noise. Wind-noise is asignificant problem particularly in directional microphones, which aremore sensitive to this disturbance. Accordingly, the invention will bedescribed with reference to a preferred embodiment in which an electretcondenser type directional microphone is used, but is not in any senselimited thereto.

In FIG. 1 a main part 1 of a cellular phone transmitter unit is providedwith a directional microphone pick up 2. The microphone pick up 2 issurrounded by a pick up housing 3 forming a chamber 4 having apredetermined cross-sectional area and a predetermined volume, whichchamber 4 encloses the microphone pick up 2. The chamber 4 includes atleast one sound passage opening 5, preferably a plurality of soundpassage openings 5′, 5″, 5′″, each opening 5′, 5″, 5″′ provided with awind noise reduction element 6. The number of wind noise reductionelements 6′, 6″, 6″′ can be any suitable number and is by no meanslimited to a particular number. The microphone pick up 2, the housing 3,the sound passage openings 5′, 5″, 5″′ and the noise reduction element6′, 6″, 6″ all together provide a directional microphone unit 10, whichcan be positioned in connection to a mouthpiece (not shown) provided ina front panel (not shown) of a portable electronic device (not shown).This is not shown in more detail since it is well known for a personskilled in the art of portable electronic devices.

Now is referred also to FIG. 2. Preferably, the housing 3 has the shapeof a cylinder, provided with a number of relatively large sound passageopenings (holes) arranged in all directions, for instance extending in alongitudinally direction of a jacket surface 7. Preferably, there isalso provided a sound passage 5 opening in a side surface 8.

In a microphone unit 10 according to the invention, part of the airstream which includes wind-noise is interrupted or blocked by themouthpiece (not shown), and part is able to pass through the soundpassage openings 5, 5′, 5″ to enter the chamber 4. Because of theinteraction between chamber 4 volume, openings 5, 5′, 5″ and wind noisereduction element 6, the air particle velocity, forming the wind, is noteasily able to enter the chamber and produce wind-noise in themicrophone pick up unit.

Now is referred to FIG. 3. The wind noise reduction element 6 could forinstance comprise one single layer such as a mesh made of metal, orpolymer material. The mesh can be of conventional type comprising wires12 with openings 13. The mesh can also be made of textile fabrics suchas cotton fabric or the like.

Typically, the ratio between the chamber size and the density of themesh is arranged to maintain a desired level of directionality from themicrophone pick up unit. Similarly the cross-sectional area and volumeof the chamber may be determined experimentally to achieve the desiredreduction in wind-noise.

Because the sensitivity of a microphone with respect to an air streamhas, in general, a proportional relationship with the speed of theimpinging air stream, it has been found that by decreasing the speed ofthe air stream as just described, wind-noise due to the air stream canbe reduced to an almost negligible level. However, it has been foundthat the sound or speaking voice signal or sound wave is transmitted ina normal manner so that the reproduced speaking voice is not adverselyaffected.

Accordingly, it is seen that the inventive microphone unit providesgreatly reduced sensitivity to wind-noise, is non-expensive, since noelectronics or software is required, and offer good overall frequencyresponse characteristics. The microphone unit is small in size,typically two to three times the size of the miniature microphonecapsule. The reduction can vary from 15-30 dB depending on the amount ofdirectionality that must be maintained. More reduction implies lessdirectionality.

Although the invention has been described with reference to particularpreferred embodiments, it is to be understood by those skilled in theart that various changes and modifications can be made without departingfrom the spirit and scope of the invention.

1. A microphone for a mobile electronic device, the microphonecomprising: a microphone pick up housing having a cylindrical shieldingsurface defining a cylindrical chamber therein wherein the cylindricalshielding surface has at least three elongated holes therethrough,wherein a length of each of the elongated holes in a longitudinaldirection of the cylindrical chamber is greater than a width thereof ina direction orthogonal with respect to the longitudinal directionwherein the at least three elongated holes are aligned in thelongitudinal direction; a microphone pick up located in the cylindricalchamber defined by the microphone pick up housing wherein the microphonepick up is surrounded by the at least three elongated holes; and a noisereduction element covering the elongated holes, wherein the microphonepick up comprises a directional condenser type microphone pick up thatis surrounded by the at least three elongated holes, and wherein thedirectional condenser type microphone pick up is canted at an anglerelative to the longitudinal direction of the cylindrical chamber.
 2. Amicrophone according to claim 1 wherein the microphone pick up housinghas an end surface that is perpendicular with respect to thelongitudinal direction and wherein the end surface has an end soundpassage opening therethrough.
 3. A microphone according to claim 2further comprising: a second noise reduction element covering the endsound passage opening therethrough.
 4. A microphone according to claim 1wherein the noise reduction element comprises a noise reduction elementon each of the at least three elongated holes.
 5. A microphone accordingto claim 1 wherein the noise reduction element comprises a mesh.
 6. Amicrophone according to claim 5 wherein the mesh comprises a metal mesh.7. A microphone according to claim 5 wherein the mesh comprises a nylonmesh.
 8. A microphone according to claim 1 wherein the noise reductionelement comprises a mesh having a plurality of layers.
 9. A cellularphone comprising a front panel; a mouthpiece provided in the frontpanel; and a directional microphone unit adjacent the mouthpiece,wherein the directional microphone unit comprises, a microphone pick uphousing having a cylindrical shielding surface defining cylindricalchamber therein wherein the cylindrical shielding surface has at leastthree elongated holes therethrough, wherein a length of each of theelongated holes in a longitudinal direction of the cylindrical chamberis greater than a width thereof in a direction orthogonal with respectto the longitudinal direction wherein the at least three elongated holesare aligned in the longitudinal direction; a directional condenser typemicrophone pick up located in the cylindrical chamber defined by themicrophone pick up housing wherein the microphone pick up is surroundedby the at least three elongated holes; and a noise reduction elementcovering the elongated holes; wherein the directional condenser typemicrophone pick up is surrounded by the at least three elongated holes,and wherein the directional condenser type microphone pick up is cantedat an angle relative to the longitudinal direction of the cylindricalchamber.
 10. A cellular phone according to claim 9 wherein themicrophone pick up housing has an end surface that is perpendicular withrespect to the longitudinal direction and wherein the end surface has anend sound passage opening therethrough.
 11. A cellular phone accordingto claim 10 further comprising: a second noise reduction elementcovering the end sound passage opening therethrough.
 12. A cellularphone according to claim 9 wherein the noise reduction element comprisesa noise reduction element on each of the at least three elongated holes.13. A cellular phone according to claim 9 wherein the noise reductionelement comprises a mesh.
 14. A cellular phone according to claim 13wherein the mesh comprises a metal mesh.
 15. A cellular phone accordingto claim 13 wherein the mesh comprises a nylon mesh.
 16. A cellularphone according to claim 9 wherein the noise reduction element comprisesa mesh having a plurality of layers.